1. Field of the Invention
This invention relates to a punching device, more particular to a punching device including an ejecting unit for preventing a cutout portion of a workpiece cut by a punch from being raised during restoration of the punch to an upper position.
2. Description of the Related Art
As illustrated in FIGS. 1 and 2, U.S. Pat. No. 6,428,248 discloses a conventional punching device that includes a housing 90, a die part 91 mounted in a lower side of the housing 90, and a punch 92 mounted in an upper side of the housing 90 and slidable toward the die part 91 to provide a shear force to cut a workpiece 9 disposed on a top wall of the die part 91. The punch 92 includes inner and outer blades 921, 922 that cooperatively define an accommodating space 920 for receiving an elastic ejecting member 93 therein. As such, the elastic ejecting member 93 is required to have a structure with a pattern the same as that of the accommodating space 920. The die part 91 is formed with holes 910 for extension of the inner and outer blades 921, 922 therein during punching. In operation, when the punch 92 is moved from an upper position (see FIG. 1) to a lower position (see FIG. 2), the elastic ejecting member 93 undergoes a process that it first presses the workpiece 9 against the top wall of the die part 91 when the workpiece 9 is cut to form a desired cutout portion having a pattern the same as that of the accommodating space 920, and is subsequently compressed by the punch 92 and the top wall of the die part 91 as the top wall of the die part 91 is gradually moved into the accommodating space 920 and the inner and outer blades 921, 922 are respectively and gradually moved into the holes 910 in the die part 91. When the punch 92 is restored from the lower position to the upper position, the elastic ejecting member 93 elastically pushes the cutout portion of the workpiece 9 out of the accommodating space 920 so that the cutout portion can remain on the top wall of the die part 91 for subsequent removal therefrom. However, when the pattern of the cutout portion of the workpiece 9 to be produced is complicated or has exceptionally thin segments, manufacture of the elastic ejecting member 93 or a spring, the structure of which has the same pattern as the cutout portion, is difficult and even if the elastic ejecting member 93 can be manufactured, insertion of it into the accommodating space 920 would be very difficult. Moreover, even if the elastic ejecting member 93 can be inserted into the accommodating space 920, the accommodating space 920 would be insufficient to permit deformation of the elastic ejecting member 93.